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Gallagher CI, Bishop DP, Lockwood TE, Rawling T, Vandenberg RJ. Methods for negating the impact of zinc contamination to allow characterization of positive allosteric modulators of glycine receptors. Front Mol Neurosci 2024; 17:1392715. [PMID: 38979476 PMCID: PMC11228362 DOI: 10.3389/fnmol.2024.1392715] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Accepted: 06/07/2024] [Indexed: 07/10/2024] Open
Abstract
Zinc is a ubiquitous contaminant in many buffers, purified products and common labware that has previously been suggested to impact on the results of functional GlyR studies and may inadvertently cause the effectiveness of some GlyR modulators to be over-estimated. This could greatly impact the assessment of potential drug-candidates and contribute to the reduced effectiveness of compounds that reach clinical stages. This is especially true for GlyR modulators being developed for pain therapeutics due to the changes in spinal zinc concentrations that have been observed during chronic pain conditions. In this study we use two-electrode voltage clamp electrophysiology to evaluate the metal chelators tricine and Ca-EDTA, and show that tricine produces inhibitory effects at GlyRα1 that are not mediated by zinc. We also utilized the zinc insensitive W170S mutation as a tool to validate metal chelators and confirm that zinc contamination has not impacted the examination of lipid modulators previously developed by our lab. This study helps to further develop methods to negate the impact of contaminating zinc in functional studies of GlyRs which should be incorporated into future studies that seek to characterize the activity of novel modulators at GlyRs.
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Affiliation(s)
- Casey I Gallagher
- Discipline of Pharmacology, School of Medical Sciences, University of Sydney, Sydney, NSW, Australia
| | - David P Bishop
- Hyphenated Mass Spectrometry Laboratory, Faculty of Science, University of Technology Sydney, Broadway, NSW, Australia
| | - Thomas E Lockwood
- Hyphenated Mass Spectrometry Laboratory, Faculty of Science, University of Technology Sydney, Broadway, NSW, Australia
| | - Tristan Rawling
- School of Mathematical and Physical Sciences, Faculty of Science, The University of Technology Sydney, Sydney, NSW, Australia
| | - Robert J Vandenberg
- Discipline of Pharmacology, School of Medical Sciences, University of Sydney, Sydney, NSW, Australia
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The Role of Zinc in Modulating Acid-Sensing Ion Channel Function. Biomolecules 2023; 13:biom13020229. [PMID: 36830598 PMCID: PMC9953155 DOI: 10.3390/biom13020229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 01/17/2023] [Accepted: 01/18/2023] [Indexed: 01/26/2023] Open
Abstract
Acid-sensing ion channels (ASICs) are proton-gated, voltage-independent sodium channels widely expressed throughout the central and peripheral nervous systems. They are involved in synaptic plasticity, learning/memory, fear conditioning and pain. Zinc, an important trace metal in the body, contributes to numerous physiological functions, with neurotransmission being of note. Zinc has been implicated in the modulation of ASICs by binding to specific sites on these channels and exerting either stimulatory or inhibitory effects depending on the ASIC subtype. ASICs have been linked to several neurological and psychological disorders, such as Alzheimer's disease, Parkinson's disease, ischemic stroke, epilepsy and cocaine addiction. Different ASIC isoforms contribute to the persistence of each of these neurological and psychological disorders. It is critical to understand how various zinc concentrations can modulate specific ASIC subtypes and how zinc regulation of ASICs can contribute to neurological and psychological diseases. This review elucidates zinc's structural interactions with ASICs and discusses the potential therapeutic implications zinc may have on neurological and psychological diseases through targeting ASICs.
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Gallagher CI, Ha DA, Harvey RJ, Vandenberg RJ. Positive Allosteric Modulators of Glycine Receptors and Their Potential Use in Pain Therapies. Pharmacol Rev 2022; 74:933-961. [PMID: 36779343 PMCID: PMC9553105 DOI: 10.1124/pharmrev.122.000583] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2022] [Revised: 04/26/2022] [Accepted: 05/13/2022] [Indexed: 11/22/2022] Open
Abstract
Glycine receptors are ligand-gated ion channels that mediate synaptic inhibition throughout the mammalian spinal cord, brainstem, and higher brain regions. They have recently emerged as promising targets for novel pain therapies due to their ability to produce antinociception by inhibiting nociceptive signals within the dorsal horn of the spinal cord. This has greatly enhanced the interest in developing positive allosteric modulators of glycine receptors. Several pharmaceutical companies and research facilities have attempted to identify new therapeutic leads by conducting large-scale screens of compound libraries, screening new derivatives from natural sources, or synthesizing novel compounds that mimic endogenous compounds with antinociceptive activity. Advances in structural techniques have also led to the publication of multiple high-resolution structures of the receptor, highlighting novel allosteric binding sites and providing additional information for previously identified binding sites. This has greatly enhanced our understanding of the functional properties of glycine receptors and expanded the structure activity relationships of novel pharmacophores. Despite this, glycine receptors are yet to be used as drug targets due to the difficulties in obtaining potent, selective modulators with favorable pharmacokinetic profiles that are devoid of side effects. This review presents a summary of the structural basis for how current compounds cause positive allosteric modulation of glycine receptors and discusses their therapeutic potential as analgesics. SIGNIFICANCE STATEMENT: Chronic pain is a major cause of disability, and in Western societies, this will only increase as the population ages. Despite the high level of prevalence and enormous socioeconomic burden incurred, treatment of chronic pain remains limited as it is often refractory to current analgesics, such as opioids. The National Institute for Drug Abuse has set finding effective, safe, nonaddictive strategies to manage chronic pain as their top priority. Positive allosteric modulators of glycine receptors may provide a therapeutic option.
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Affiliation(s)
- Casey I Gallagher
- Molecular Biomedicine, School of Medical Sciences, University of Sydney, Sydney, Australia (C.I.G., D.A.H., R.J.V.) and Biomedical Science, School of Health and Behavioural Sciences and Sunshine Coast Health Institute, University of the Sunshine Coast, Maroochydore, Australia (R.J.H.)
| | - Damien A Ha
- Molecular Biomedicine, School of Medical Sciences, University of Sydney, Sydney, Australia (C.I.G., D.A.H., R.J.V.) and Biomedical Science, School of Health and Behavioural Sciences and Sunshine Coast Health Institute, University of the Sunshine Coast, Maroochydore, Australia (R.J.H.)
| | - Robert J Harvey
- Molecular Biomedicine, School of Medical Sciences, University of Sydney, Sydney, Australia (C.I.G., D.A.H., R.J.V.) and Biomedical Science, School of Health and Behavioural Sciences and Sunshine Coast Health Institute, University of the Sunshine Coast, Maroochydore, Australia (R.J.H.)
| | - Robert J Vandenberg
- Molecular Biomedicine, School of Medical Sciences, University of Sydney, Sydney, Australia (C.I.G., D.A.H., R.J.V.) and Biomedical Science, School of Health and Behavioural Sciences and Sunshine Coast Health Institute, University of the Sunshine Coast, Maroochydore, Australia (R.J.H.)
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4
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Nutraceuticals: A source of benefaction for neuropathic pain and fibromyalgia. J Funct Foods 2022. [DOI: 10.1016/j.jff.2022.105260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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5
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Zinc Inhibits TRPV1 to Alleviate Chemotherapy-Induced Neuropathic Pain. J Neurosci 2017; 38:474-483. [PMID: 29192128 DOI: 10.1523/jneurosci.1816-17.2017] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Revised: 10/24/2017] [Accepted: 11/16/2017] [Indexed: 01/25/2023] Open
Abstract
Zinc is a transition metal that has a long history of use as an anti-inflammatory agent. It also soothes pain sensations in a number of animal models. However, the effects and mechanisms of zinc on chemotherapy-induced peripheral neuropathy remain unknown. Here we show that locally injected zinc markedly reduces neuropathic pain in male and female mice induced by paclitaxel, a chemotherapy drug, in a TRPV1-dependent manner. Extracellularly applied zinc also inhibits the function of TRPV1 expressed in HEK293 cells and mouse DRG neurons, which requires the presence of zinc-permeable TRPA1 to mediate entry of zinc into the cytoplasm. Moreover, TRPA1 is required for zinc-induced inhibition of TRPV1-mediated acute nociception. Unexpectedly, zinc transporters, but not TRPA1, are required for zinc-induced inhibition of TRPV1-dependent chronic neuropathic pain produced by paclitaxel. Together, our study demonstrates a novel mechanism underlying the analgesic effect of zinc on paclitaxel-induced neuropathic pain that relies on the function of TRPV1.SIGNIFICANCE STATEMENT The chemotherapy-induced peripheral neuropathy is a major limiting factor affecting the chemotherapy patients. There is no effective treatment available currently. We demonstrate that zinc prevents paclitaxel-induced mechanical hypersensitivity via inhibiting the TRPV1 channel, which is involved in the sensitization of peripheral nociceptors in chemotherapy. Zinc transporters in DRG neurons are required for the entry of zinc into the intracellular side, where it inhibits TRPV1. Our study provides insight into the mechanism underlying the pain-soothing effect of zinc and suggests that zinc could be developed to therapeutics for the treatment of chemotherapy-induced peripheral neuropathy.
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Hardt S, Heidler J, Albuquerque B, Valek L, Altmann C, Wilken-Schmitz A, Schäfer MK, Wittig I, Tegeder I. Loss of synaptic zinc transport in progranulin deficient mice may contribute to progranulin-associated psychopathology and chronic pain. Biochim Biophys Acta Mol Basis Dis 2017; 1863:2727-2745. [DOI: 10.1016/j.bbadis.2017.07.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Revised: 06/30/2017] [Accepted: 07/14/2017] [Indexed: 12/11/2022]
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Gonkowski S, Rowniak M, Wojtkiewicz J. Zinc Transporter 3 (ZnT3) in the Enteric Nervous System of the Porcine Ileum in Physiological Conditions and during Experimental Inflammation. Int J Mol Sci 2017; 18:ijms18020338. [PMID: 28178198 PMCID: PMC5343873 DOI: 10.3390/ijms18020338] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Revised: 01/28/2017] [Accepted: 02/03/2017] [Indexed: 01/19/2023] Open
Abstract
Zinc transporter 3 (ZnT3) is a member of the solute-linked carrier 30 (SLC 30) zinc transporter family. It is closely linked to the nervous system, where it takes part in the transport of zinc ions from the cytoplasm to the synaptic vesicles. ZnT3 has also been observed in the enteric nervous system (ENS), but its reactions in response to pathological factors remain unknown. This study, based on the triple immunofluorescence technique, describes changes in ZnT3-like immunoreactive (ZnT3-LI) enteric neurons in the porcine ileum, caused by chemically-induced inflammation. The inflammatory process led to a clear increase in the percentage of neurons immunoreactive to ZnT3 in all "kinds" of intramural enteric plexuses, i.e., myenteric (MP), outer submucous (OSP) and inner submucous (ISP) plexuses. Moreover, a wide range of other active substances was noted in ZnT3-LI neurons under physiological and pathological conditions, and changes in neurochemical characterisation of ZnT3⁺ cells in response to inflammation depended on the "kind" of enteric plexus. The obtained results show that ZnT3 is present in the ENS in a relatively numerous and diversified neuronal population, not only in physiological conditions, but also during inflammation. The reasons for the observed changes are not clear; they may be connected with the functions of zinc ions and their homeostasis disturbances in pathological processes. On the other hand, they may be due to adaptive and/or neuroprotective processes within the pathologically altered gastrointestinal tract.
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Affiliation(s)
- Sławomir Gonkowski
- Department of Clinical Physiology, Faculty of Veterinary Medicine, Oczapowskiego 13, University of Warmia and Mazury, 10-718 Olsztyn, Poland.
| | - Maciej Rowniak
- Department of Comparative Anatomy, Faculty of Biology, Plac Łódzki 3, University of Warmia and Mazury, 10-727 Olsztyn, Poland.
| | - Joanna Wojtkiewicz
- Department of Pathophysiology, Faculty of Medical Sciences, Warszawska 30, University of Warmia and Mazury, 10-082 Olsztyn, Poland.
- Laboratory for Regenerative Medicine, Faculty of Medical Sciences, University of Warmia and Mazury, Olsztyn, 10-082 Olsztyn, Poland.
- Foundation for Nerve Cells Regeneration, Warszawska 30, 10-082 Olsztyn, Poland.
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8
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Choi BY, Kim IY, Kim JH, Kho AR, Lee SH, Lee BE, Sohn M, Koh JY, Suh SW. Zinc transporter 3 (ZnT3) gene deletion reduces spinal cord white matter damage and motor deficits in a murine MOG-induced multiple sclerosis model. Neurobiol Dis 2016; 94:205-12. [DOI: 10.1016/j.nbd.2016.06.018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2016] [Revised: 05/20/2016] [Accepted: 06/27/2016] [Indexed: 12/25/2022] Open
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9
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Korvela M, Lind AL, Wetterhall M, Gordh T, Andersson M, Pettersson J. Quantification of 10 elements in human cerebrospinal fluid from chronic pain patients with and without spinal cord stimulation. J Trace Elem Med Biol 2016; 37:1-7. [PMID: 27473826 DOI: 10.1016/j.jtemb.2016.06.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Revised: 05/23/2016] [Accepted: 06/01/2016] [Indexed: 12/14/2022]
Abstract
Neuropathic pain affects 1-10% of the general population and is caused by a lesion or disease of the somatosensory nervous system. Spinal cord stimulation (SCS), a method where implanted electrodes stimulate the spinal cord, has been successfully used to treat drug-resistant neuropathic pain, but the mechanism of action is largely unknown. Studies show that SCS changes the protein levels in CSF (cerebrospinal fluid) of pain patients. Several neurological conditions have been shown to alter the elemental composition of CSF. Therefore changes in the levels of ions and trace elements in the CSF may correspond to SCS use. This study used ICP-MS (Inductively coupled plasma mass spectrometry) and ICP-AES (Inductively coupled plasma atomic emission spectroscopy) to quantify 10 elements in CSF from chronic neuropathic pain patients using SCS. The element concentrations in CSF from patients with SCS treatment on/off, were measured. No effect on the element concentrations in CSF from treatment with SCS could be detected. Also, the elemental concentrations in pooled CSF from patients without chronic neuropathic pain was determined and compared to the patients using SCS. The concentration of the elements Ca, Sr, Na, K, P, Mg and Ti were, significantly higher in patients compared to the CSF-control.
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Affiliation(s)
- Marcus Korvela
- Department of Chemistry-BMC, Uppsala University, Box 599, 751 24 Uppsala, Sweden
| | - Anne-Li Lind
- Department of Chemistry-BMC, Uppsala University, Box 599, 751 24 Uppsala, Sweden; Department of Surgical Sciences, Anaesthesiology and Intensive Care, Uppsala University, 751 85 Uppsala, Sweden
| | | | - Torsten Gordh
- Department of Surgical Sciences, Anaesthesiology and Intensive Care, Uppsala University, 751 85 Uppsala, Sweden
| | - Marit Andersson
- Department of Chemistry-BMC, Uppsala University, Box 599, 751 24 Uppsala, Sweden
| | - Jean Pettersson
- Department of Chemistry-BMC, Uppsala University, Box 599, 751 24 Uppsala, Sweden.
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Kwon A, Jeon SM, Hwang SH, Kim JH, Cho HJ. Expression and functional role of metallothioneins I and II in the spinal cord in inflammatory and neuropathic pain models. Brain Res 2013; 1523:37-48. [PMID: 23726995 DOI: 10.1016/j.brainres.2013.05.037] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2012] [Revised: 04/19/2013] [Accepted: 05/21/2013] [Indexed: 11/19/2022]
Abstract
In this study, the expression and functional role of metallothioneins I and II (MT-I/II) were evaluated in the spinal cord in rat models of inflammatory and neuropathic pain. Complete Freund's adjuvant (CFA) injection into the hindpaw induced an increase in MT-I/II protein expression in bilateral dorsal and ventral horns throughout the spinal cord, while chronic constriction injury (CCI) of the sciatic nerve induced an increase in MT-I/II expression in the ipsilateral dorsal and ventral horns of the lower lumbar spinal cord. Increased MT-I/II immunoreactivity was predominantly localized to vascular endothelial cells. CFA injection- and CCI-induced MT-I/II expression was inhibited by intrathecal administration of MT-I siRNA. Treatment with MT-I siRNA before CFA injection or at early time points after CCI resulted in a significant attenuation of mechanical allodynia and thermal hyperalgesia, while treatment at later time points had no effect on established pain behaviors. Our results suggest that endogenous MT-I/II might play an important role in the pathogenesis of pain behaviors, participating in the initiation of inflammatory and neuropathic pain rather than in their maintenance.
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Affiliation(s)
- Aram Kwon
- Department of Anatomy, School of Medicine, Kyungpook National University, 2-101, Dongin Dong, Daegu 702-422, South Korea
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11
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Su R, Mei X, Wang Y, Zhang L. Regulation of zinc transporter 1 expression in dorsal horn of spinal cord after acute spinal cord injury of rats by dietary zinc. Biol Trace Elem Res 2012; 149:219-26. [PMID: 22565470 DOI: 10.1007/s12011-012-9414-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Accepted: 04/02/2012] [Indexed: 12/27/2022]
Abstract
Zinc concentrations in the dorsal horn of spinal cord are important for wound healing, neurological function, and reproduction. However, the response of the spinal cord to alterations in dietary zinc is unknown in rats after spinal cord injury (SCI). The current study explored cellular zinc levels and zinc transporter 1 (ZnT1) expression in the dorsal horn of spinal cord with different dietary zinc after SCI. A hundred and forty-four male Wistar rats were randomly divided into four groups: sham-operated group (30 mg Zn/kg), zinc-high dietary SCI model group (ZH, 180 mg Zn/kg), zinc-adequate dietary SCI model group (30 mg Zn/kg), and marginal zinc-deficient dietary SCI model group (MZD, 5 mg Zn/kg). To test the hypothesis that dietary zinc may regulate role of ZnT1 expression in dorsal horn after acute SCI, we traced ZnT1 proteins and zinc ions with immunohistochemistry, western blot, and autometallography. Zinc and ZnT1 levels of the dorsal horn in ZH significantly increased after surgery (P < 0.05), reached peak level (P < 0.05) on the seventh day, and subsequently levels of their expression began to decrease. But zinc levels and ZnT1 expression of spinal cord in MZD dietary groups decreased (P < 0.05) in SCI. There was a positive correlation between ZnT1 protein and zinc content in spinal cord (R = 0.49880, P = 0.0492). We found that both zinc and ZnT1 expressions in spinal cord are regulated by dietary zinc. These results indicate that dietary zinc may regulate the expression of ZnT1 in the dorsal horn of spinal cord after SCI. ZnT1 may, at the same time, play a significant role in the maintenance of zinc homeostasis in SCI.
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Affiliation(s)
- Ribao Su
- Department of Orthopaedic Surgery, Affiliated Hospital of Liaoning Medical University, No. 3-40 Songpo Road, Guta District, Jinzhou City, Liaoning Province, 121001, China
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12
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Nozaki C, Vergnano AM, Filliol D, Ouagazzal AM, Le Goff A, Carvalho S, Reiss D, Gaveriaux-Ruff C, Neyton J, Paoletti P, Kieffer BL. Zinc alleviates pain through high-affinity binding to the NMDA receptor NR2A subunit. Nat Neurosci 2011; 14:1017-22. [PMID: 21725314 DOI: 10.1038/nn.2844] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2010] [Accepted: 04/19/2011] [Indexed: 02/07/2023]
Abstract
Zinc is abundant in the central nervous system and regulates pain, but the underlying mechanisms are unknown. In vitro studies have shown that extracellular zinc modulates a plethora of signaling membrane proteins, including NMDA receptors containing the NR2A subunit, which display exquisite zinc sensitivity. We created NR2A-H128S knock-in mice to investigate whether Zn2+-NR2A interaction influences pain control. In these mice, high-affinity (nanomolar) zinc inhibition of NMDA currents was lost in the hippocampus and spinal cord. Knock-in mice showed hypersensitivity to radiant heat and capsaicin, and developed enhanced allodynia in inflammatory and neuropathic pain models. Furthermore, zinc-induced analgesia was completely abolished under both acute and chronic pain conditions. Our data establish that zinc is an endogenous modulator of excitatory neurotransmission in vivo and identify a new mechanism in pain processing that relies on NR2A NMDA receptors. The study also potentially provides a molecular basis for the pain-relieving effects of dietary zinc supplementation.
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Affiliation(s)
- Chihiro Nozaki
- Institut de Génétique et Biologie Moléculaire et Cellulaire, Illkirch, France
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13
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Chang M, Smith S, Thorpe A, Barratt MJ, Karim F. Evaluation of phenoxybenzamine in the CFA model of pain following gene expression studies and connectivity mapping. Mol Pain 2010; 6:56. [PMID: 20846436 PMCID: PMC2949723 DOI: 10.1186/1744-8069-6-56] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2010] [Accepted: 09/16/2010] [Indexed: 11/24/2022] Open
Abstract
Background We have previously used the rat 4 day Complete Freund's Adjuvant (CFA) model to screen compounds with potential to reduce osteoarthritic pain. The aim of this study was to identify genes altered in this model of osteoarthritic pain and use this information to infer analgesic potential of compounds based on their own gene expression profiles using the Connectivity Map approach. Results Using microarrays, we identified differentially expressed genes in L4 and L5 dorsal root ganglia (DRG) from rats that had received intraplantar CFA for 4 days compared to matched, untreated control animals. Analysis of these data indicated that the two groups were distinguishable by differences in genes important in immune responses, nerve growth and regeneration. This list of differentially expressed genes defined a "CFA signature". We used the Connectivity Map approach to identify pharmacologic agents in the Broad Institute Build02 database that had gene expression signatures that were inversely related ('negatively connected') with our CFA signature. To test the predictive nature of the Connectivity Map methodology, we tested phenoxybenzamine (an alpha adrenergic receptor antagonist) - one of the most negatively connected compounds identified in this database - for analgesic activity in the CFA model. Our results indicate that at 10 mg/kg, phenoxybenzamine demonstrated analgesia comparable to that of Naproxen in this model. Conclusion Evaluation of phenoxybenzamine-induced analgesia in the current study lends support to the utility of the Connectivity Map approach for identifying compounds with analgesic properties in the CFA model.
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Affiliation(s)
- Meiping Chang
- Indications Discovery Research Unit, Pfizer Global Research and Development, Chesterfield, MO 63017, USA
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14
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Jiang Q, Papasian CJ, Wang JQ, Xiong ZG, Chu XP. Inhibitory regulation of acid-sensing ion channel 3 by zinc. Neuroscience 2010; 169:574-83. [PMID: 20580786 DOI: 10.1016/j.neuroscience.2010.05.043] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2010] [Revised: 05/14/2010] [Accepted: 05/18/2010] [Indexed: 02/03/2023]
Abstract
Acid-sensing ion channel 3 (ASIC3) is a proton-gated, voltage-insensitive Na(+) channel that is expressed primarily in peripheral sensory neurons and plays an important role in pain perception, particularly as a pH sensor following cardiac ischemia. We previously reported that ASIC3 currents are not affected by zinc at nanomolar concentrations. In this study, we examined the potential role of micromolar zinc in the regulation of ASIC3. In CHO cells expressing ASIC3, we found that ASIC3 currents triggered by dropping the pH from 7.4 to 6.0 were inhibited by pretreatment with zinc in a concentration-dependent manner; the half-maximum inhibitory concentration of zinc was 61 muM. ASIC currents activated by a relatively small drop in pH from 7.4 to 7.2 or 7.0 were also subject to inhibition by zinc. The inhibition was fast and pH independent, and occurred within a relatively narrow range of zinc concentrations between 30 and 300 muM. Further, increasing extracellular Ca(2+) concentrations from 2 to 10 mM failed to affect inhibition of ASIC3 currents by zinc. Experimentally elevating intracellular zinc levels did not affect the inhibition of ASIC3 currents by equal concentrations of extracellular zinc, and modification of cysteine or histidine residues had no effect on the inhibition of ASIC3 currents by zinc. These collective results suggest that zinc is an important regulator of ASIC3 at physiological concentrations, that zinc inhibits ASIC3 in a pH- and Ca(2+)-independent manner, and that inhibition of ASIC3 currents is dependent upon the interaction of zinc with extracellular domain(s) of ASIC3.
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Affiliation(s)
- Q Jiang
- Department of Basic Medical Science, School of Medicine, University of Missouri-Kansas City, 2411 Holmes Street, Kansas City, MO 64108, USA
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15
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Hu H, Bandell M, Petrus MJ, Zhu MX, Patapoutian A. Zinc activates damage-sensing TRPA1 ion channels. Nat Chem Biol 2009; 5:183-90. [PMID: 19202543 DOI: 10.1038/nchembio.146] [Citation(s) in RCA: 169] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2008] [Accepted: 01/13/2009] [Indexed: 02/07/2023]
Abstract
Zinc is an essential biological trace element. It is required for the structure or function of over 300 proteins, and it is increasingly recognized for its role in cell signaling. However, high concentrations of zinc have cytotoxic effects, and overexposure to zinc can cause pain and inflammation through unknown mechanisms. Here we show that zinc excites nociceptive somatosensory neurons and causes nociception in mice through TRPA1, a cation channel previously shown to mediate the pungency of wasabi and cinnamon through cysteine modification. Zinc activates TRPA1 through a unique mechanism that requires zinc influx through TRPA1 channels and subsequent activation via specific intracellular cysteine and histidine residues. TRPA1 is highly sensitive to intracellular zinc, as low nanomolar concentrations activate TRPA1 and modulate its sensitivity. These findings identify TRPA1 as an important target for the sensory effects of zinc and support an emerging role for zinc as a signaling molecule that can modulate sensory transmission.
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Affiliation(s)
- Hongzhen Hu
- Genomics Institute of the Novartis Research Foundation, 10675 John Jay Hopkins Drive, San Diego, California 92121, USA
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16
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Tang HB, Miyano K, Nakata Y. Modulation of the Substance P Release From Cultured Rat Primary Afferent Neurons by Zinc Ions. J Pharmacol Sci 2009; 110:397-400. [DOI: 10.1254/jphs.09033sc] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
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17
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Chen EI, McClatchy D, Park SK, Yates JR. Comparisons of mass spectrometry compatible surfactants for global analysis of the mammalian brain proteome. Anal Chem 2008; 80:8694-701. [PMID: 18937422 DOI: 10.1021/ac800606w] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Methods for the global analysis of protein expression offer an approach to study the molecular basis of disease. Studies of protein expression in tissue, such as brain, are complicated by the need for efficient and unbiased digestion of proteins that permit identification of peptides by shotgun proteomic methods. In particular, identification and characterization of less abundant membrane proteins has been of great interest for studies of brain physiology, but often proteins of interest are of low abundance or exist in multiple isoforms. Parsing protein isoforms as a function of disease will be essential. In this study, we develop a digestion scheme using detergents compatible with mass spectrometry that improves membrane protein identification from brain tissue. We show the modified procedure yields close to 5,000 protein identifications from 1.8 mg of rat brain homogenate with an average of 25% protein sequence coverage. This procedure achieves a remarkable reduction in the amount of starting material required to observe a broad spectrum of membrane proteins. Among the proteins identified from a mammalian brain homogenate, 1897 (35%) proteins are annotated by Gene Ontology as membrane proteins, and 1225 (22.6%) proteins are predicted to contain at least one transmembrane domain. Membrane proteins identified included neurotransmitter receptors and ion channels implicated in important physiological functions and disease.
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Affiliation(s)
- Emily I Chen
- Department of Chemical Physiology, The Scripps Research Institute, California 92037, USA
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Current World Literature. Curr Opin Anaesthesiol 2008; 21:684-93. [DOI: 10.1097/aco.0b013e328312c01b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Abstract
Acid-sensing ion channels (ASICs) are broadly expressed in the CNS, including the spinal cord. However, very little is known about the properties of ASICs in spinal cord neurons compared with brain. We show here that ASIC1a and ASIC2a are the most abundant ASICs in mouse adult spinal cord and are coexpressed by most neurons throughout all the laminas. ASIC currents in cultured embryonic day 14 mouse dorsal spinal neurons mainly flow through homomeric ASIC1a (34% of neurons) and heteromeric ASIC1a plus 2a channels at a ratio of 2:1 (83% of neurons). ASIC2b only has a minor contribution to these currents. The two channel subtypes show different active pH ranges and different inactivation and reactivation kinetics supporting complementary functional properties. One striking property of native dorsal spinal neuron currents and recombinant currents is the pH dependence of the reactivation process. A light sustained acidosis induces a threefold slow-down of the homomeric ASIC1a (from pH 7.4 to pH 7.3) and heteromeric ASIC1a plus 2a (from pH 7.4 to pH 7.2) current reactivation (T(0.5) increasing from 5.77 to 16.84 s and from 0.98 to 3.2 s, respectively), whereas a larger acidosis to pH 6.6 induces a 32-fold slow-down of the ASIC1a plus 2a current reactivation (T(0.5) values increasing to 31.30 s). The pH dependence of ASIC channel reactivation is likely to modulate neuronal excitability associated with repetitive firing in response to extracellular pH oscillations, which can be induced, for example, by intense synaptic activity of central neurons.
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